well my dads 1995 nissan pickup has valve tap, i replaced the exhaust maniflod because it was cracked so i thought that would fix the problem but it has not. Its just the same, do you think the cats can be the culprit?

No probably not the cats if there is no leak. Easiest thing to do is check the valve train by replacing the oil with a high mileage oil. If the ticking disappears or quiets a lot then you know you have something worn in the valvetrain. My wife's 2.5 engine in her Mazda 626 was making a tapping noise and it would get loud when it was time to change the oil. It was the lifters.

Dunno about your specific truck, but the Japanese used solid lifter cams for a lot longer than the American manufacturers. My wife's 626 had them and I could always tell when they needed adjustments, you couldn't squeal th etires from a stop when they needed adjustment. That would happen long before they started to tap. It could be that.

Other than that, a quart of Marvel Mystery oil inthe crankcase will usually clean up varnished hydraulic lifters right quick.

Where did it crack. Typically it will be do to a casting flaw or a bolt over tightened and during heat a contraction crack out from the bolt

from the middle of the two collectors, but it cracked on its own, i didnt touch it when it cracked, i just hr=eard valve tap so i checked the exhaust manifold and sure enough it was cracked so i replaced it but it did not stop the valve tap. so what do i do guys?

im going to call the dealer to see if they are solid or hydraulic because i dont have acces to "Alldata" at the moment (i really should get the damn program) and im not about to take **** apart when i can just call.

COOL!the lifters are solid, they will be able to be adjusted. anyone know of any tricks to get the codes out of this truck without a scanner, you know like on chrystlers in which you can turn the key three times then you turn it on and the check engine light flashes to give you codes. there prolly is not a way but i can try.